Roving mobile units utilizing cellular mobile communication systems are known. Typically, a mobile unit is provided with a communication resource, generally an RF (radio frequency) channel, that is usable for at least a first base site covering a geographical area. During periods of high RF communication system use, as the mobile unit roves to at least a second base site geographical area, the mobile unit may be denied continued assignment to a communication resource in the second base site geographical area, forcing termination of communication resource use by the mobile unit. Forced termination is a more severe problem than simply denial of initial assignment to an RF communication resource, and hence is highly undesirable. There is a need for a RF communication system that provides a next RF communication resource to a mobile unit that utilizes a first RF communication resource and roves from a first geographical base site area to another geographical base site area not served by the first RF communication resource.